[Not Applicable]
1. Field of the Invention
The present invention relates-to a golf ball. More specifically, the present invention relates to a two-piece golf ball with a cover layer composed of an ionomer blend, a core containing polybutadiene, tungsten, and other materials, and a tubular lattice structure aerodynamic pattern.
2. Description of the Related Art
Two-piece golf balls with ionomer covers have been in existence since the 1960""s. The core is typically solid, and the cover is usually a hard ionomer material. The two-piece golf balls of the prior art provide added distance while giving up feel.
The traditional golf ball, as readily accepted by the consuming public, is spherical with a plurality of dimples, with each dimple having a circular cross-section. Many golf balls have been disclosed that break with this tradition, however, for the most part these non-traditional golf balls have been commercially unsuccessful.
Most of these non-traditional golf balls still attempt to adhere to the Rules Of Golf as set forth by the United States Golf Association (USGA) and The Royal and Ancient Golf Club of Saint Andrews (RandA). As set forth in Appendix III of the Rules of Golf, the weight of the ball shall not be greater than 1.620 ounces avoirdupois (45.93 gm), the diameter of the ball shall be not less than 1.680 inches (42.67 mm) which is satisfied if, under its own weight, a ball falls through a 1.680 inches diameter ring gauge in fewer than 25 out of 100 randomly selected positions, the test being carried out at a temperature of 23xc2x11xc2x0 C., and the ball must not be designed, manufactured or intentionally modified to have properties which differ from those of a spherically symmetrical ball. Also, the Rules of Golf limit the initial velocity of a golf ball to 250 feet (76.2 m) per second (a two percent maximum tolerance allows for an initial velocity of 255 per second) and the overall distance to 280 yards (256 m) plus a six percent tolerance for a total distance of 296.8 yards (the six percent tolerance may be lowered to four percent). A complete description of the Rules of Golf is available on the USGA web page at ww_Hlt509050176w_Hlt509050176.usga.org or at the RandA web page at www.randa.org. Thus, the initial velocity and overall distance of a golf ball must not exceed these limits in order to conform to the Rules of Golf.
One example is Shimosaka et al., U.S. Pat. No. 5,916,044, for a Golf Ball that discloses the use of protrusions to meet the 1.68 inch (42.67 mm) diameter limitation of the USGA and RandA. The Shimosaka patent discloses a golf ball with a plurality of dimples on the surface and a few rows of protrusions that have a height of 0.001 to 1.0 mm from the surface. Thus, the diameter of the land area is less than 42.67 mm.
Another example of a non-traditional golf ball is Puckett et al., U.S. Pat. No. 4,836,552 for a Short Distance Golf Ball, which discloses a golf ball having brambles instead of dimples in order to reduce the flight distance to half of that of a traditional golf ball in order to play on short distance courses.
Another example of a non-traditional golf ball is Pocklington, U.S. Pat. No. 5,536,013 for a Golf Ball, which discloses a golf ball having raised portions within each dimple, and also discloses dimples of varying geometric shapes such as squares, diamonds and pentagons. The raised portions in each of the dimples of Pocklington assists in controlling the overall volume of the dimples.
Another example is Kobayashi, U.S. Pat. No. 4,787,638 for a Golf Ball, which discloses a golf ball having dimples with indentations within each of the dimples. The indentations in the dimples of Kobayashi are to reduce the air pressure drag at low speeds in order to increase the distance.
Yet another example is Treadwell, U.S. Pat. No. 4,266,773 for a Golf Ball, which discloses a golf ball having rough bands and smooth bands on its surface in order to trip the boundary layer of air flow during flight of the golf ball.
Aoyama, U.S. Pat. No. 4,830,378, for a Golf Ball With Uniform Land Configuration, discloses a golf ball with dimples that have triangular shapes. The total flat land area of Aoyama is no greater than 20% of the surface of the golf ball, and the objective of the patent is to optimize the uniform land configuration and not the dimples.
Another variation in the shape of the dimples is set forth in Steifel, U.S. Pat. No. 5,890,975 for a Golf Ball And Method Of Forming Dimples Thereon. Some of the dimples of Steifel are elongated to have an elliptical cross-section instead of a circular cross-section. The elongated dimples make it possible to increase the surface coverage area. A design patent to Steifel, U.S. Pat. No. 406,623, has all elongated dimples.
A variation on this theme is set forth in Moriyama et al., U.S. Pat. No. 5,722,903, for a Golf Ball, which discloses a golf ball with traditional dimples and oval shaped dimples.
A further example of a non-traditional golf ball is set forth in Shaw et al., U.S. Pat. No. 4,722,529, for Golf Balls, which discloses a golf ball with dimples and 30 bald patches in the shape of a dumbbell for improvements in aerodynamics.
Another example of a non-traditional golf ball is Cadorniga, U.S. Pat. No. 5,470,076, for a Golf Ball, which discloses each of a plurality of dimples having an additional recess. It is believed that the major and minor recess dimples of Cadorniga create a smaller wake of air during flight of a golf ball.
Oka et al., U.S. Pat. No. 5,143,377, for a Golf Ball, discloses circular and non-circular dimples. The non-circular dimples are square, regular octagonal, regular hexagonal and amount to at least forty percent of the 332 dimples on the golf ball of Oka. These non-circular dimples of Oka have a double slope that sweeps air away from the periphery in order to make the air turbulent.
Machin, U.S. Pat. No. 5,377,989, for Golf Balls With Isodiametrical Dimples, discloses a golf ball having dimples with an odd number of curved sides and arcuate apices to reduce the drag on the golf ball during flight.
Lavallee et al., U.S. Pat. No. 5,356,150, discloses a golf ball having overlapping elongated dimples to obtain maximum dimple coverage on the surface of the golf ball.
Oka et al., U.S. Pat. No. 5,338,039, discloses a golf ball having at least forty percent of its dimples with a polygonal shape. The shapes of the Oka golf ball are pentagonal, hexagonal and octagonal.
Although the prior art has set forth numerous variations for the surface of a golf ball, there remains a need for a two-piece golf ball having a surface that minimizes the volume needed to trip the boundary layer of air at low speed while providing a low drag level at high speeds.
One aspect of the present invention is a golf ball having a core, a cover and a lattice structure aerodynamic pattern. The core has a diameter of 1.53 inches to 1.55 inches. The core is composed of polybutadiene, zinc oxide in an amount of 7 to 15 parts per hundred parts of polybutadiene, zinc diacryalate in an amount of 30 to 50 parts per hundred parts of polybutadiene, an initiator in an amount of 0.1 to 1.0 parts per hundred parts of polybutadiene, and tungsten in an amount of 5 to 10 parts per hundred parts of polybutadiene. The core has a PGA compression of 60 to 75 points. The cover has a thickness of 0.060 inch to 0.090 inch. The cover is composed of an ionomer blend formed from a high acid ionomer resin neutralized with sodium and a terpolymer neutralized with magnesium. The cover has a Shore D hardness ranging from 52 to 58. The golf ball has a COR at 143 feet per second that is greater than 0.782 points.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.